Hydraulic hoist for tow trucks



Oct. 24, 1967 R. E. LARDNER I Filed Feb.

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INVENTOR. ROBERT E. LARDNER United States Patent Office 3,348,809 Patented Oct. 24, 1967 .3,34 ,8 HYDRAULIC HOIST FOR TOW TRUCKS Robert E. Lardner, Edmonton, Alberta, Canada, as signor to Western Pneumatics Ltd., Edmonton, Al'- berta, Canada Filed Feb. 7, 1966, Ser. No. 525,575 2 Claims. (Cl. 254*124) This invention relates to a hydraulic hoist for lifting and handling heavy objects, and particularly to hoists for use with automotive towing vehicles.

The invention is particularly directed to a hydraulic hoist suited for mounting on the rear portion of a towing vehicle for co-operation with a towing bridle, whereby a second vehicle may be suitably raised into a towing position.

Hoists presently used on vehicles for such purposes as towing are generally of large size and complex structure. Owing to the necessity of securely fastening the hoist to the vehicle and the obstructive nature and form of the hoists presently used, the vehicle is generally not usable except in a lifting or towing role.

An object of the presene invention is to provide hoist for use in a towing vehicle adapted to occupy a minimum amount of space in the vehicle when not in use.

Another object of the present invention is to provide a simple and robust hoisting device readily actuated by hydraulic power means.

Still another object of the present invention is to provide a hoist for use in conjunction with a towing bridle to raise vehicles to be towed into a suitable towing position. A further object is to provide a securing device to hold the load independently of the hoist while in transit.

A further object of the present invention is to provide a hydraulically actuated hoist having a dual range of loading capacity.

These and other objects of the invention are achieved by means of a hydraulically operated hoist for use on a truck, comprising: pivotal arm means; load attachment means secured to the arm means adjacent one end thereof; an elongated support frame including a pair of side members; pivot means extending between the side members in supporting relation with the arm means; hydraulically operable piston and cylinder actuator means extending within the support frame and attached at one end thereto; means to selectively provide pressure fluid to the actuator means; and means attaching the other end of the actuator to the arm means to provide pivotal movement of the load attachment means in response to changes in the effective length of the actuator means, said attaching means enabling the arm means to be positioned in close coextensive relation with the support frame, whereby the space requirement of the hoist when not in use is reduced to a minimum.

An embodiment of the invention is described with reference to the following drawings wherein:

FIGURE 1 shows a plan view of a hoist according to the present invention;

FIGURE 2 ShOWs a side elevation of the device taken on 22 of FIGURE 1; and

FIGURE 3 is a view of the device mounted on a truck as used for raising vehicles into a suitable position for towing.

Referring to FIGURES l and 2, the hoist 20 comprises a cantilevered arm 21 pivotally mounted in a frame 33 and actuated by a hydraulic actuator 43.

The arm 21 is of inverted U-form having a top portion 22 and side portions 23, 24. A load attachment bracket 25 is attached to one end of the arm.

A pair of transversely aligned apertures 26 in the side portions 23, 24 of the arm 21 are adapted to receive pivot pin 50 for supporting arm 21. Arm 21 has a pair of actuating bracket arms 27, 28 attached to and extending downwardly from the side portions 23, 24, and having transversely aligned apertures 29 to receive a pivot pin 51 for connection to the actuator 43. V

The hoist support frame 33 includes a pair of side members 34, 34a having attachment flanges 35, 35a at the bottom edges thereof for attachment to a mount such as the bed 55 of a truck shown in FIGURE 3. The side members 34, 34a of the frame are spaced from each other by a back plate 36 and a front plate 37 which provide a substantially rigid structure. The first pair of apertures 38 extend through the side wall members 34, 34a in transverse alignment to receive pivot pin 50 for the arm 21, while a second pair of apertures 39 also extending transversely through the frame side members 34, 34a in transverse alignment are adapted to receive pivot pin 52 for the actuator 43. p 7

The actuator 43 comprises a cylinder 44 and an output member or piston rod 45. The actuator cylinder 44' is secured to the frame 33 by means of a cylinder mounting bracket 46 having an aperture 47 therethrough to receive pivot pin 52, while the piston rod 45 is 'similiary apertured as shown at 48 to receive pivot pin 51 for attachment to the actuating bracket arms 27, 28. Pressurized hydraulic fluid is supplied to the actuator, which is double-acting, by way of flexible pressure supply lines 49.

The three main components of the hoist are assembled in co-operating relation by means of pivot pins 50, 51 and 52. The arm pivot pin 50 on which the loading arm 21 is mounted extends through apertures 38 in the support frame side members 34, 34a and through apertures 26 in the loading arm side portions 23, 24. The actuator cylinder pivot pin 52 is located in apertures 39 of the support frame side members 34, 34a and passes through the aperture 47 in the cylinder mounting bracket 46.

The loading arm drive pin 51 secures the output member 45 of the actuator 43 to the actuator bracket arms 27, 28 of the loading arm 21.

In the case of the pin 50, attached to the frame 33, spacers 53 provide centering of the arm between the frame side members 34, 34a. The pins 50, 51 and 52 are secured in position relative to the other components by conventional means such as circlips, drive pins or split pins (not shown).

An inextensible hook member 58 is shown attached to the rear portion of the frame 33, so that when the hoist is in use, the load on the actuator 43 and the arm 21 need not be continuously sustained by these parts. In addition to, or as an alternative to the link 58, it is contemplated that a locking pin may be inserted through the arm 21 and engaged within holes in the side members 34, 34a of the support frame 33, in order to im mobilize the arm 21 in a desired position or positions.

As shown in FIGURE 2, a control valve may be used in co-operation with a source of pressurized hydraulic fluid such as an accumulator connected to a suitable pump, providing pressurized fluid through the flexible lines 48 to the actuator cylinder 44.

When mounted on a truck bed 55 (FIGURE 3) for use in conjunction with an A-frame stabilizer 56, the hoist according to the present invention provides a ready means for lifting a portion of a vehicle 57.

It will be seen that the control valve of the present arrangement can be mounted in an accessible position adjacent the tailgate of the towing vehicle.

When not in use, or when a vehicle has been raised into a desired towing position and secured by the hook member 58, the loading arm 21 can then be returned to a substantially horizontal position in which the truck bed is substantially unobstructed, and is available for other requirements and uses.

In addition to possessingthe capability of raising a vehicle into the towing position, it will be seen that by permitting a lifting cable to pass in contact with the rear end of the lifting arm 21 very large lifting forces may be exerted upon the cable. The provision of transverse cable stabilizing members to locate the cable on the arm 21 at the rear portion thereof adjacent the pivot point is contemplated.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. A hydraulically operated hoist for use on a truck comprising: lift arm means, said arm means having a load attachment means secured thereto adjacent one end thereof. and actuator attachment means securedthereto adjacent the other end thereof; an elongated support frame including a pair of spaced apart side members; pivot means extending transversely between said side members at the rearward end thereof in snpportingrelation with said arm at a point intermediate the ends thereof; a double acting hydraulically operable piston and cylinder actuator extending between said support frame side members and having one end pivotally attached at the forward end of said support frame; means to selectively provide fluid pressure to said actuator, said actuator and actuator attachingmeans enabling said arm means to be rotated to a position substantially perpendicular to said support frame tion and to a position in close coextensive relation with said support frame when said actuator is in an extended position, whereby the space requirement of the hoist when not in use is reduced to a minimum.

2. A hoist as claimed in claim 1 wherein said arm means includes an upper portion with a load attachment bracket secured to one end thereof, a pair of side walls extending from the upper portion having a pair of transversely aligned apertures extending therethrough located intermediate the ends of the arm means to receive a pivot pin References Cited UNITED STATES PATENTS 2,373,469 4/1945 Grime 254-8 2,702,988 3/1955 Rhoads et al 254-2 2,789,788 4/1957 Wilson 254--2 2,950,085 8/ 1960 Lizzadro 254-124 OTHELL M. SIMPSON, Primary Examiner.

when said actuator is in a retracted posi-. 

1. A HYDRAULICALLY OPERATED HOIST FOR USE ON A TRUCK COMPRISING: LIFT ARM MEANS, SAID ARM MEANS HAVING A LOAD ATTACHMENT MEANS SECURED THERETO ADJACENT ONE END THEREOF SAID ACTUATOR ATTACHMENT MEANS SECURED THERETO ADJACENT THE OTHER END THEREOF; AN ELONGATED SUPPORT FRAME INCLUDING A PAIR OF SPACED APART SIDE MEMBERS; PIVOT MEANS EXTENDING TRANSVERSELY BETWEEN SAID SIDE MEMBERS AT THE REARWARD END THEREOF IN SUPPORTING RELATION WITH SAID ARM AT A POINT INTERMEDIATE THE ENDS THEREOF; A DOUBLE ACTING HYDRAULICALLY OPERABLE PISTON AND CYLINDER ACTUATOR EXTENDING BETWEEN SAID SUPPORT FRAME SIDE MEMBERS AND HAVING ONE END PIVOTALLY ATTACHED AT THE FORWARD END OF SAID SUPPORT FRAME; MEANS TO SELECTIVELY PROVIDE FLUID PRESSURE TO SAID ACTUATOR, SAID ACTUATOR AND ACTUATOR ATTACHING MEANS ENABLING SAID ARM MEANS TO BE ROTATED TO A POSITION SUBSTANTIALLY PERPENDICULAR TO SAID SUPPORT FRAME WHEN SAID ACTUATOR IS IN A RETRACTED POSITION AND TO A POSITION IN CLOSE COEXTENSIVE RELATION WITH SAID SUPPORT FRAME WHEN SAID ACTUATOR IS IN AN EXTENDED POSITION, WHEREBY THE SPACE REQUIREMENT OF THE HOIST WHEN NOT IN USE IN REDUCED TO A MINIMUM. 